000 AXPZ20 KNHC 292116 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1948 UTC Fri Sep 29 2017 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2100 UTC. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across Central America to a 1008 MB low pres over the Gulf of Tehuantepec near 15N95W to 13N110W to 12N130W to 10N140W. A cluster of moderate convection is west of the low pres and covers from 14N to 15.5N between 96W and 97.5W. Scattered moderate convection can be found from 05N to 07N between 80W and 82W, from 13N to 15N between 99W and 102W, and from 10N to 12N between 107W and 110W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong gap winds will develop over the Gulf of Tehuantepec tonight as a ridge builds across the western Gulf of Mexico and the eastern slopes of the Sierra Madre Mountains. This gap wind event will persist during the upcoming weekend. Elsewhere, a ridge will dominate the waters west of the Baja California Peninsula producing gentle to moderate northerly winds and seas of 4-5 ft through Saturday. Northerly swell will propagate into the waters west of Baja California Norte Sunday, building seas to 6-8 ft. Fresh to locally strong S-SW winds are expected over the northern Gulf of California Sunday night through Tuesday as low pressure develops over the area. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough is currently across Central America and adjacent waters. The trough will remain close enough to the coast, either inland or just offshore, to produce active convection, primarily during the late afternoon and evening hours, over portions of Central America as well as the adjacent coastal waters during the next few days. Moderate to locally fresh SW to W winds are expected south of the monsoon trough during the upcoming weekend. Long period SW swell will continue to propagate across the offshore waters with seas of 5-7 ft through the weekend. Looking ahead, broad area of low pressure developing over Central America will cause monsoonal winds to surge to fresh to strong speeds west of Costa Rica from Sunday night through at least the middle of next week. Seas of 8 ft or higher will affect the waters beyond 200 nm off the coast from Nicaragua to Guatemala. REMAINDER OF THE AREA... A ridge extends from 1022 mb high pressure located near 32N138W to the south of the Baja california peninsula. The pressure gradient between the ridge and the monsoon trough is supporting gentle to moderate winds. Looking ahead, northerly swell will propagate into the waters north of 25N between 120W and 130W Sun through Mon night, building seas up to 11 ft along 30N by Monday. Farther south, cross equatorial southerly swell will propagate across the waters south of 02N between 105W and 135W by Tuesday, with seas building to 8-10 ft. $$ GR